Many countries recognize that the ability to access emergency services by telephone is a vital component of public safety and emergency preparedness. For example, in the United States of America the Federal Communications Commission (FCC) requires that consumers of telephone service be able to reach emergency services regardless of the technology used to place a 9-1-1 call. More specifically, the FCC requires that providers of “interconnected” Voice over Internet Protocol (VoIP) services meet Enhanced 9-1-1 (E9-1-1) obligations. E9-1-1 systems automatically provide to emergency service personnel a 9-1-1 caller's call back number and, in most cases, location information. See, e.g., http://www.fcc.gov/guides/voip-and-9-1-1-service.
Thus, for VoIP services the FCC mandates that a VoIP provider provide a location for the VoIP customer. Responses to emergency access calls, e.g., 9-1-1 calls, placed using the VoIP service are routed based on the location provided by the VoIP service. Generally, the location provided by the VoIP service is an address that was previously provided to the VoIP service by the VoIP customer. In the case of stationary VoIP equipment (such as a standard analog telephone-VoIP adapter home setup), the VoIP user, when making the 9-1-1 call, may often reasonably be assumed actually to be at the location provided to the VoIP service. However, this is not always the case, as VoIP customers may readily connect their devices, such as IP phones, to any suitable broadband connection, thereby moving their actual physical location without necessarily updating the address previously provided to the VoIP service. Moreover, many people use VoIP telephone services on mobile or wireless devices, e.g., mobile phones that are tied to a cell carrier. In these cases, the 9-1-1 call on the VoIP service may be directed to the native dialer for termination on the native cell network. VoIP services may even be offered for wireless devices that do not have any association with a separate cell network. In these cases, there is no “native” dialer over which the 9-1-1 call can be directed.
Many if not most cell phones are now equipped with Global Positioning System (GPS) functionality, and as such are able to supply via a telephone service the GPS coordinates of the cell phone when making an emergency access call. While FCC and other regulations impose requirements regarding accuracy of the GPS coordinates that must be provided, the GPS coordinates may not be entirely unambiguous or definitively precise in some topological environments. For example, in a dense urban environment several dwelling units or business offices/establishments may be within the ambit of the GPS coordinates. Consider, for example, the situation of a multi-story apartment or office building in which the GPS coordinates may not provide sufficient differentiation between floors of the building, or sufficient specificity with respect to adjacent or proximate units (e.g., hotel rooms) on a same floor.
What is desired therefore, and an exemplary advantage of the technology disclosed herein, are methods, systems, and techniques that more accurately reflect where a user is located so that responses to emergency access calls may be correctly and precisely directed.